Raman Filters

                                               Filter Types for Raman Spectroscopy Applications

In Raman spectroscopy, an intense laser beam is used to excite a sample and the Raman "finger print" is measured by a dispersive or Fourier Transform spectrometer. Optical filters are used to prevent the undesired light from reaching the spectrometer and drowning out the relatively weak Raman signal.

There are four basic types of filters to choose from: a long wave pass (LWP) edge filter, a short wave pass (SWP) edge filter, a notch filter, and a laser line filter (each shown below). Laser line filters transmit only the laser and block all other light, while notch filter block only the laser line while passing both long and shorter wavelengths.  By using these two filters together, both Stokes and Anti-Stokes Raman scattering can be measured simultaneously.